\documentclass{standalone}
\usepackage{gravimeter,particles}
\usetikzlibrary{backgrounds}
\begin{document}
    \begin{tikzpicture}
      \def\radius{4.95cm}
      \pdfsetrandomseed11
      \clip[rounded corners=2em]
        (-\radius-1em,-\radius-1em)
        rectangle
        (\radius+1em,\radius+1em)
      ; 
      \node{\particles[scale=1,opacity=0.8,draw=violet,fill=violet!30][9][12][1.2]};
      \node{
          \gravimeter[scale=0.5,fg5={draw=violet,ultra thick}]%
        };
      \node{\particles[scale=1,draw=violet,opacity=0.7,fill=violet!30][9][12][0.8]};
      \draw[
          ultra thick,
          violet,fill=violet, opacity=1,even odd rule,
          rounded corners=2em,
          draw=black
        ]
        circle(\radius)
        (-\radius-1em,-\radius-1em)
        rectangle 
        (\radius+1em,\radius+1em)
      ; 
      \node
        [
          anchor=south east,
          scale=1.4,
          font=\Huge\sffamily,
          outer sep=0.2em
        ]
        at(\radius+1em,-\radius-1em)
        {\color{white}%
          \ifdefined\grat%
            grat%
          \else%
            gr@%
          \fi}
      ;
    \end{tikzpicture}
\end{document}
